page_title: DD tank
section_title: Later flotation screen use
hierarchical_section_title: DD tank / History / Later flotation screen use
context_page_description: DD or Duplex Drive tanks, nicknamed "Donald Duck tanks", were a type of amphibious swimming tank developed by the British during the Second World War. The phrase is mostly used for the Duplex Drive variant of the M4 Sherman medium tank, that was used by the Western Allies during and after the Normandy Landings in June 1944.
  DD tanks worked by erecting a 'flotation screen' around the tank, which enabled it to float, and had two propellers powered by the tank's engine to drive them in the water.
  The DD tanks were one of the many specialized assault vehicles, collectively known as Hobart's Funnies, devised to support the planned invasion of Europe.
context_section_description: Designs were made to give the Cromwell and Churchill the DD treatment, but these were never completed. A floating, flame-thrower equipped version of the Universal Carrier was tested, as was a flamethrower-equipped DD Sherman. This towed an armoured fuel trailer, like those used by the Churchill Crocodile. The trailer, in the water, was supported by an inflatable flotation device.
  After the war, the Centurion was tested with a flotation screen and duplex drive. By the end of the 1950s, development of DD tanks had ceased, partly because main battle tanks were becoming too heavy to be practically made to swim – although experiments were carried-out in the mid-1960s with a floating Centurion that used a similar system, but with rigid panels instead of a flexible screen.
  The 38 tonne Vickers MBT was fitted with a flotation screen that allowed it to swim.
  Medium and light vehicles continued to be made amphibious by the use of flotation screens into the 1980s, but without the DD. Instead, they used the movement of their standard running gear (e.g. tracks) for water propulsion also. These included the Swedish Stridsvagn 103 (S-Tank), the American M551 Sheridan light tank, the British FV432 Armoured personnel carrier, the Mark IV version of the Ferret armoured car and early versions of the American M2 Bradley Infantry Fighting Vehicle. Of these, only the FV432 and the Bradley remain in service and current versions lack flotation screens.
caption: M2 Bradley Infantry Fighting Vehicle emerging from the water at Fort Benning (1983). This M2 uses a screen but is not DD
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